1. Field of the Invention
This invention relates to internal combustion engines and the like and, more particularly, but not by way of limitation, to a cylinder head bolt plug for cylinder heads which permits increased air charge to the combustion chamber, decreased exhaust back pressure, and a lower frequency of cracked cylinder heads.
2. Discussion
It is known in the art relating to internal combustion engines to provide one or more combustion chambers having inlet ports with openings for intermittently admitting fuel and air to the combustion chambers. It has been previously recognized that an air intake system designed for free breathing and maximum air flow increases high speed performance and combustion efficiency. A known method for increasing air flow through the air intake system is to modify the configuration of the air inlets by reshaping or recontouring the interior walls of the air inlets to reduce pressure drop and increase air velocity through the air inlets. Modification of the air inlets is normally accomplished by removing metal from the interior walls of the air inlets.
Although the reason for the improvement produced by modification of the air inlets is not fully understood, it is believed that the reshaping and recontouring of the interior walls of the air inlets reduce the thickness of the boundary layer along the interior walls. With a thinner boundary layer, the flow of air through the air inlets to the combustion chamber would be closer to the interior walls and act to follow the interior walls in laminar flow, thus enhancing flow of air through the air inlets and into the combustion chamber.
Traditional cylinder head designs require bores or through holes through which cylinder head bolts pass to secure the cylinder head to the engine block. Many of the bores or through holes are relatively shorter and typically require cylinder head bolts of from one and one-half inches to one and three-fourths inches in length. Other bores or through holes pass through thicker portions of the cylinder head and require cylinder head bolts of from three inches to three and three-fourths inches in length. The relatively longer bores or through holes limit the extent to which metal can be removed from the interior walls of the air inlets to reshape and recountour the interior walls of the air inlets and increase air flow. Moreover, the maximum increase in air flow frequently results from reshaping and recontouring the interior walls nearest the bores or through holes.
It is further known in the art relating to internal combustion engines that a reduction in exhaust back pressure improves performance of the engine. Just as an air intake system designed for free breathing and maximum air flow increases high speed performance and combustion efficiency, an exhaust outlet system designed for maximum flow of exhaust gases also increases high speed performance and combustion efficiency. A known method for increasing flow of exhaust gases through the exhaust outlet system is to modify the configuration of the exhaust gas outlets by reshaping or recontouring the interior walls of the exhaust gas outlets to reduce exhaust back pressure and increase flow of exhaust gases through the exhaust gas outlets. Modification is normally accomplished by removing metal from the interior walls of the exhaust gas outlets.
As in the case of the air inlets, the relatively longer cylinder head bolt bores or through holes limit the extent to which metal can be removed from the interior walls of the exhaust gas outlets to reshape and recountour the interior walls of the exhaust gas outlets and reduce exhaust back pressure.
It is also well known in the art relating to internal combustion engines that cracking of the cylinder heads is caused, at least in part, by flexing of the cylinder heads as a result of tightening of the relatively longer cylinder head bolts.
The cylinder head bolt plug removes the limitations on reshaping and recontouring both air inlets and exhaust gas outlets imposed by the relatively longer bores or through holes through which cylinder head bolts pass to secure the cylinder head to the block. The cylinder head bolt plug also reduces flexing and cracking of cylinder heads by replacing longer cylinder head bolts with shorter inner-fitting cylinder head bolts.